1. Field of the Invention
This invention relates to disk drive suspensions, and more particularly to load beams for such suspensions having an integrated gimbal flexure, that is a gimbal flexure formed from the metal web of the load beam and unitary and integral with the load beam. Certain of the gimbal flexure components are partially etched to provide reduced stiffness and increased gimbal responsiveness. A flexible circuit carrying conductors is connected to the gimbal flexure frame outriggers to complete the gimbal flexure frame with less stiffness than a completely steel flexure, and is connected to the flexure tongue to limit flexure tongue excursions.
2. Related Art
In disk drives, the read-write head is carried in a slider suspended from a suspension flexure comprising a tongue typically gimbaled on a dimple. As sliders decrease in size, design problems that can be overlooked in larger devices become critical with pico and nano sized sliders the need for increased flexibility of the flexure becomes paramount. A convenient style of flexure is one integrated into the load beam by forming the flexure features (flexure frame and tongue) at the time of load beam formation from a single, unitary web of stainless steel. The steel of the load beam is more properly designed for the requirements of the load beam and is often too stiff and thus ill-suited for forming a flexure, particularly where the slider is pico or nano-sized and lacks mass
Symmetric gimbal flexure design provides a relatively high pitch and roll stiffness. Reducing the gimbal flexure stiffness increases the tendency to unwanted out-of-plane motion. The invention provides a more flexible gimbal flexure having a softer response characteristic, but offers the convenience of fabrication as an integral part of the load beam. Additionally, the invention uses wireless electrical connection through a flexible circuit comprising a laminate of a base layer, a dielectric layer and plural conductors. The flexible circuit is not relied on to form the flexure and thus problems of attachment between the flexible circuit and the load beam are obviated. The flexible circuit, however, does enter into formation of the gimbal flexure as a softer component than the load beam steel, and also serves to limit unwanted excursions of the tongue and control its out-of-plane movement. Further, in the present invention, the slider is permitted to pitch about the transverse axis (normal to the long axis). The gimbal flexure is free to move with the flexible circuit attached at the gimbal flexure front end and thus utilize the softer properties of the flexible circuit in comparison with the steel. As a further feature the flexure tongue has its distal end as its free end rather than the conventional proximate end being free, for improved gimbaling and linear pitch motion. Additionally, the invention, using an integrated flexure, avoids the welding of the gimbal flexure to the load beam and provides a bond pad situs that may be more precise than found with welded flexible circuit flexure devices.
It is an object of the invention, accordingly, to provide a disk drive suspension having a low stiffness gimbal flexure, partially formed from the load beam, and partially from flexible circuit. It is another object to provide a suspension with a gimbal flexure having a frame and tongue etched from the load beam, the frame being locally partially etched to reduce frame stiffness, but not the tongue, and the frame sides defining an open end and coupled to each other at their distal ends across the frame open end by the flexible circuit, the flexible circuit itself in its nonconductive components being reduced to its dielectric layer except where connected to the frame and tongue to provide a soft linking of the frame sides across the open end of the frame.
These and other objects of the invention to become apparent hereinafter are realized in a disk drive suspension having a low stiffness gimbal flexure and comprising a flexible circuit and a one-piece load beam and gimbal flexure, the flexible circuit comprising a laminate of a conductor, a plastic film layer and a metal layer, the load beam supporting the flexible circuit and having a distal end comprising a rigid portion, the load beam rigid portion being selectively etched to define within the plane of the rigid portion the gimbal flexure comprising a flexure frame generally spaced from the rigid portion across a gap, the flexure frame being locally connected at its left and right sides to the rigid portion across the gap to support the flexure frame in place, the gimbal flexure further comprising a flexure tongue cantilevered from the proximate end of the flexure frame toward the flexure frame distal end, the flexible circuit having a distal portion extending beyond the load beam rigid portion and connected to the distal end of the flexure tongue and to each of the flexure frame sides, the flexible circuit distal portion being free of its the metal layer except where so connected.
In this and like embodiments, typically: the load beam rigid portion has a first thickness, and the gimbal flexure frame is reduced to a second, lesser thickness for lower stiffness in the gimbal flexure; the gimbal flexure frame is surface etched to the lesser thickness; the tongue has a greater thickness than the gimbal flexure frame; the load beam rigid portion has a first thickness, the gimbal flexure frame has a second, lesser thickness, and the tongue has the thickness of the load beam rigid portion; the gimbal flexure frame is generally U-shaped; the gimbal flexure frame has a proximate end, left and right legs extending distally from the proximate end to define the flexure frame sides, and an open distal end, the flexure frame being supported on the load beam rigid portion intermediate the length of the flexure frame legs; the flexure frame legs have distal terminals and flexible circuit distal portion is connected to the flexure frame leg terminals; and/or the flexure tongue has a distal free end, the flexible circuit distal portion being connected to the tongue distal free end in free end motion limiting relation.
In a particularly preferred embodiment, the invention provides a disk drive suspension comprising a flexible circuit and a one-piece load beam and low stiffness gimbal flexure, the flexible circuit comprising a laminate of a conductor, a plastic film layer and a metal layer, the load beam supporting the flexible circuit and having a distal end comprising a rigid portion having a first thickness, the load beam rigid portion being selectively etched through its the first thickness to define within the plane of the rigid portion the gimbal flexure comprising a generally U-shaped flexure frame generally spaced from the rigid portion across an etching-produced gap, the flexure frame having a proximate end, left and right legs extending distally from the proximate end, and an open distal end, the flexure frame being locally connected at its the left and right legs to the rigid portion across the gap to support the flexure frame in place, the flexure frame having a lesser thickness than the first thickness, the flexure further comprising a flexure tongue having the first thickness and cantilevered from the proximate base end of the flexure frame toward the flexure frame open distal end, the flexible circuit having a distal portion extending beyond the load beam rigid portion and connected to the distal end of the flexure tongue and to each of the flexure frame legs across the flexure frame open distal end, the flexible circuit distal portion being free of its the metal layer except where connected to the flexure tongue or flexure frame legs, whereby flexure tongue movement is limited by the flexible circuit film layer.
In this and like embodiments, typically: the gimbal flexure frame is surface etched to the lesser thickness; the flexure frame legs have distal terminals and flexible circuit distal portion is connected to the flexure frame leg terminals; and the flexure tongue has a distal free end, the flexible circuit distal portion being connected to the tongue distal free end in free end motion limiting relation.
The invention in its method aspects provides the method of forming a disk drive suspension having a low stiffness gimbal flexure comprising a flexure frame and tongue formed in one piece with a load beam of a given thickness, including setting off the flexure frame from the load beam rigid portion by etching around the flexure frame, reducing the frame thickness by partial etch, setting off the flexure tongue from the flexure frame by etching while maintaining the flexure tongue thickness at the given thickness, and completing the flexure frame by connecting a flexible conductor comprising a laminate of a metal layer, a plastic film layer and conductors to the distal end of the frame, connecting the flexible conductor to the flexure tongue, and removing the metal layer in the flexible conductor except at each locus of connection of the flexible conductor to the flexure frame and tongue.